The year is 2035 and humankind subsists in a desolate netherworld following the eradication of 99% of the Earth's population, a holocaust that makes the planet's surface uninhabitable, and mankind's destiny uncertain. A desperate group of scientists secure a reluctant volunteer, Cole, to embark on a dangerous mission back to the year 1996, where they hope he can help unravel this apocalyptic nightmare before it completely erases humanity from the planet. When Cole arrives in 1996, he meets Jeffrey Goines, the unstable son of a renowned scientist, and Dr. Kathryn Railly, a psychiatrist and author whose initial alarm over his prophetic warnings of the world's fate soon turns to conviction, and she comes to believe that mankind may indeed be doomed. While also questioning his own sanity, Cole struggles with Railly to unravel the mystery with his only two clues: a haunting childhood memory and a series of puzzling symbols from a group known only as The Army of the Twelve Monkeys.